常见英语面试题

first.The difference etween Vector and ArrayList

1.ArrayList is not synchronized while Vector is.
2.ArrayList has no defaule size while vector has a default size of 10.
3.ArrayList don't define any increment size while Vector has.
4.ArrayList can be seenn directly without any iterator while vector rrequices an iterator to display all it's content.

second.The difference between Hashtable and HashMap
The hashMap class is roughly equivalent to hashTable.
except that it is unsynchronized and permits nulls.
HashMap can not guarantee that the order of the Map will remain constant over time.

third:Diference betweent inerface and abstract class
  1.interface no implementation.abstract class can have partial implementation
  2. a class can implement several interfaces but one class can only extend one abstract class.
  3.interfaces are slow as it required extra indirection to find corresponding method in the actual class.

similarities:
neither abstract classes  or interface can be instantiated.